1. Field of the Invention
The present invention relates to a disk drive system wherein a disk drive for treating a read-only disk and a readable/writable disk is connected via a bus to a host computer for controlling the disk drive and commands and data are transmitted between the host computer and the disk drive via the bus.
2. Description of the Related Art
Recently a disk drive system has been put to practical use, which is of the type wherein a disk drive for treating a read-only disk (CD-ROM) and a disk drive for treating a readable/writable optical disk (R/W-OD) are selectively connected via a bus to a host computer for controlling the selected disk drive to transmit commands and data between the host computer and the selected disk drive via the bus.
Besides, a disk drive system has been put to practical use, which is of the type wherein a disk drive for treating a readable/writable optical disk (R/W-OD) is connected via a bus to a host computer for controlling the disk drive and commands and data are transmitted between the host computer and the disk drive via the bus.
However, there has been no system wherein a single disk drive can treat selectively a read-only disk or a compact disk ROM (CD-ROM) and a readable/writable optical disk (R/W-OD).
In the case of the CD-ROM, the signal read from the CD-ROM should be subjected to signal processing and data processing corresponding to the format of the CD-ROM as read-only disk, thereby reproducing data. In the case of the R/W-OD, data fed from a host computer should be recorded on the R/W-OD in accordance with the format thereof, or data on the disk is read and sent to the host computer.
The host computer, however, cannot determine whether the currently loaded disk is the CD-ROM or R/W-OD. Thus, the host computer inquires of the disk drives whether the loaded disk is the CD-ROM or R/W-OD. Based on a response from the disk drives, the host computer chooses a command to be used and transmits it to one of the disk drive. Consequently, the structure of the disk drive system and the soft processing on the host computer side becomes complex and the load of software processing increases.